With concerns about identifying ever-changing strains of HIV, hepatitis, and other blood born pathogens, the use of blood bank whole blood as a source for blood components in non-emergency surgical procedures has been disfavored. As a result, it is advantageous to draw blood from a patient, extract the needed blood component, and then reintroduce the blood component into the patient during a surgical procedure. Plasminogen is exemplary of a blood component that is separated from a patient's own blood and reintroduced into the patient.
Plasminogen is a component of the fibrolytic system and is the plasmaprotein precursor of plasmin, a serine protease. Plasmin is well known to function in fibrinolysis and fibrinogenolysis, as well as digesting factor IXa, and the activation of zymogens, among its many functions. Plasmin is injected systemically for the treatment of acute thrombolytic disorders. The injection of plasmin into a human eye has been shown to induce posterior vitreous detachment, as detailed in U.S. Pat. No. 5,304,118.
While methods of isolating plasminogen are well known to the art, these methods have required considerable time and equipment that precluded plasmin extraction and isolation simultaneous with a surgical procedure. As a result, blood collection from a patient and plasmin extraction and isolation had to occur prior to patient anesthesia increasing the time and cost of the surgical procedure. Exemplary of these time consuming plasminogen purification procedures are U.S. Pat. Nos. 3,943,245; 5,371,007 and Castellino, Methods of Enzy., Vol. 80, 265-337 (1981).
A rapid method for purification of plasminogen utilized an affinity cartridge under syringe pressure to selectively bind a desired blood component. The affinity cartridge was then washed with an equilibration buffer followed by injecting an elution buffer therethrough containing a release agent for the desired blood component. This method is detailed in U.S. Pat. No. 6,207,066 and is capable of delivering active plasmin from a blood sample within tens of minutes. Unfortunately, the concentration of active plasmin is lower than otherwise could be used and is often insufficient to reproducibly induce a posterior vitreous detachment. A low plasmin concentration results in decreased biological efficacy. Thus, there exists a need for a method to purify and concentrate a blood component from a whole blood sample quickly enough that the blood draw and reintroduction of the desired blood component may occur in due course of a surgical procedure.